Semiconductor devices with alignment keys

ABSTRACT

A semiconductor device includes an alignment key on a substrate. The alignment key includes a first sub-alignment key pattern with a first conductive pattern, a second conductive pattern, and a capping dielectric pattern that are sequentially stacked on the substrate, an alignment key trench that penetrates at least a portion of the first sub-alignment key pattern, and a lower conductive pattern in the alignment key trench. The alignment key trench includes an upper trench that is provided in the capping dielectric pattern that has a first width, and a lower trench that extends downward from the upper trench and that has a second width less than the first width. The lower conductive pattern includes sidewall conductive patterns that are separately disposed on opposite sidewalls of the lower trench.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. nonprovisional patent application claims priority under 35U.S.C § 119 from, and the benefit of, Korean Patent Application10-2016-0127011, filed on Sep. 30, 2016 in the Korean IntellectualProperty Office, the contents of which are herein incorporated byreference in their entirety.

BACKGROUND Technical Field

Embodiments of the present inventive concept are directed to asemiconductor device, and more particularly, to a semiconductor memorydevice that includes an alignment key.

Discussion of the Related Art

Semiconductor devices have become increasingly integrated with thedevelopment of the electronics industry. It is challenging to fabricatea semiconductor device because of reduced process margins in an exposureprocess that defines fine patterns. High speed semiconductor devices areincreasingly in demand with the development of the electronics industry,and the development of high speed and more highly integratedsemiconductor device has been the subject of much research.

In general, to fabricate a semiconductor device, a predeterminedmaterial layer is formed on a semiconductor substrate, i.e., a wafer,and then a photolithography process is performed to form a desiredpattern. The photolithography process is carried out to form a patternby forming a photoresist layer on the semiconductor substrate on whichthe predetermined layer is formed, forming a photoresist pattern byexposing and developing the photoresist layer using a mask, and thenetching the predetermined layer using the photoresist pattern. Theexposure process has an important role in determining the fabricationaccuracy of a method for the semiconductor device. When the exposureprocess is utilized to than a predetermined pattern on the semiconductorsubstrate, a photo alignment key is used to exactly align an exposuremask.

SUMMARY

Embodiments of the present inventive concept can provide a semiconductordevice having enhanced process yield and reliability.

According to exemplary embodiments of the present inventive concept, asemiconductor device includes an alignment key on a substrate. Thealignment key comprises a first sub-alignment key pattern that includesa first conductive pattern, a second conductive pattern, and a cappingdielectric pattern that are sequentially stacked on the substrate; analignment key trench that penetrates at least a portion of the firstsub-alignment key pattern; and a lower conductive pattern in thealignment key trench. The alignment key trench comprises an upper trenchprovided in the capping dielectric pattern that has a first width; and alower trench that extends downward from the upper trench that has asecond width less than the first width. The lower conductive patternincludes sidewall conductive patterns that are separately disposed onopposite sidewalls of the lower trench.

According to exemplary embodiments of the present inventive concept, asemiconductor device comprises a substrate that includes a chip zone anda scribe lane zone; a gate line on the chip zone; and an alignment keyon the scribe lane zone. The gate line includes a gate dielectricpattern, a lower gate pattern, an upper gate pattern, and a gate cappingpattern that are sequentially stacked on the substrate. The alignmentkey comprises a first sub-alignment key pattern that includes a bufferdielectric pattern, a first conductive pattern, a second conductivepattern, and a capping dielectric pattern that are sequentially stackedon the substrate; an alignment key trench that penetrates at least aportion of the first sub-alignment key pattern, the alignment key trenchincluding an upper trench that vertically penetrates a portion of thecapping dielectric pattern and has a first width and a lower trench thatextends downward from the upper trench and has a second width less thanthe first width; and sidewall conductive patterns that are separatelydisposed on opposite sidewalls of the lower trench. The bufferdielectric pattern, the first conductive pattern, the second conductivepattern, and the capping dielectric pattern include the same materials,respectively, as the gate dielectric pattern, the lower gate pattern,the upper gate pattern, and the gate capping pattern.

According to exemplary embodiments of the present inventive concept, amethod of fabricating a semiconductor device includes providing asubstrate that includes a first region and a second region; sequentiallyforming a first dielectric layer, a lower conductive layer, an upperconductive layer, and a second dielectric layer on the substrate;forming a first mask pattern on the substrate that covers a portion ofthe second dielectric layer in the first region and completely coversthe second dielectric layer in the second region; and etching thesubstrate using the first mask pattern as an etching mask wherein a gateline is formed in the first region of the substrate. The gate lineincludes a gate dielectric pattern, a lower gate pattern, an upper gatepattern, and a gate capping pattern that are respectively formed bypatterning the first dielectric layer, the lower conductive layer, theupper conductive layer, and the second dielectric layer in the firstregion. The method further includes removing the first mask pattern;forming source/drain regions in the substrate on opposite sides of thegate line; forming a lower interlayer dielectric layer on the firstregion of the substrate; forming a second mask pattern on the substratethat has first openings on the first region that overlap thesource/drain regions and a trench-shaped second opening on the secondregion; etching portions of the lower interlayer dielectric layerexposed through the first openings using the second mask pattern to formlower contact holes that penetrate the lower interlayer dielectric layerand expose the source/drain regions, wherein the second dielectric layerand the upper conductive layer of the second region are sequentiallyetched to form a preliminary alignment key trench that exposes the lowerconductive layer; and removing the second mask pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified plan view that illustrates a semiconductor deviceaccording to exemplary embodiments of the present inventive concept.

FIG. 2 is a plan view that illustrates shapes of photo alignment keys.

FIG. 3 is a plan view that partly illustrates a semiconductor device ofFIG. 1.

FIG. 4 is a cross-sectional view taken along lines I-I′ and II-II′ ofFIG. 3.

FIGS. 5A to 5C are cross-sectional views, corresponding to line II-II′of FIG. 3, that illustrate other examples of alignment keys shown inFIGS. 3 and 4.

FIGS. 6 to 14 are cross-sectional views, corresponding to lines I-I′ andII-II′ of FIG. 3, that illustrate a method of fabricating asemiconductor device according to exemplary embodiments of the presentinventive concept.

FIGS. 15 and 16 are cross-sectional views, corresponding to lines I-I′and II-II′ of FIG. 3, that illustrate comparative examples that arecompared with exemplary embodiments of the present inventive concept.

FIG. 17 is a cross-sectional view, corresponding to lines I-I′ andII-II′ of FIG. 3, that illustrates a semiconductor device according toexemplary embodiments of the present inventive concept.

FIGS. 18A to 18C are cross-sectional views, corresponding to line II-II′of FIG. 3, that illustrate other examples of alignment keys shown inFIGS. 3 and 17.

FIGS. 19 to 22 are cross-sectional views, corresponding to lines I-I′and II-II′ of FIG. 3, that illustrate a method of fabricating asemiconductor device according to exemplary embodiments of the presentinventive concept.

FIG. 23 is a cross-sectional view, corresponding to lines I-I′ andII-II′ of FIG. 3, that illustrates a semiconductor device according toexemplary embodiments of the present inventive concept.

FIGS. 24A to 24C are cross-sectional views, corresponding to lines I-I′and II-II′ of FIG. 3, that illustrates a semiconductor device accordingto exemplary embodiments of the present inventive concept.

FIG. 25 is a plan view that illustrates a semiconductor device accordingto exemplary embodiments of the present inventive concept.

FIG. 26 is a cross-sectional view taken along lines A-A′, B-B′, and C-C′of FIG. 25.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present inventive concept willbe described in detail with reference to the accompanying drawings.

FIG. 1 is a simplified plan view that illustrates a semiconductor deviceaccording to exemplary embodiments of the present inventive concept.FIG. 2 is a plan view that illustrates shapes of photo alignment keys.

Referring to FIG. 1, a semiconductor device 10 according to anembodiment includes a chip zone 12 and a scribe lane zone 14. The chipzone 12 corresponds to one of a plurality of semiconductor chips formedon a semiconductor wafer, and the scribe lane zone 14 corresponds to aportion of scribe lane used to cut the semiconductor wafer into separatesemiconductor chips after process steps that form the semiconductorchips on the semiconductor wafer have terminated. The chip zone 12includes a cell region on which memory cells are formed and a peripheralcircuit region on which peripheral circuits that control the memorycells are formed. For example, the chip zone 12 may includemetal-oxide-semiconductor (MOS) transistors, a diode, or a resistor. Thescribe lane zone 14 includes a test device group and photo alignmentkeys 16 a and 16 b, referred to hereinafter as alignment keys.

According to embodiments, the alignment keys 16 a and 16 b have a shapesimilar to that of cell, contact, or trench. As shown in FIG. 2, thealignment keys 16 a and 16 b have various patterns AK1, AK2, and AK3. Inaccordance with their purpose, the alignment keys 16 a and 16 b can beclassified as a local alignment key, a global alignment key, aregistration alignment key, an overlay alignment key, and a measurementkey. A trench-type alignment key and a semiconductor device includingthe same will hereinafter be described in detail.

FIG. 3 is a plan view that partly illustrates the semiconductor deviceof FIG. 1. FIG. 4 is a cross-sectional view taken along lines I-I′ andII-II′ of FIG. 3.

Referring to FIGS. 3 and 4, according to embodiments, a substrate 100includes a first region R1 and a second region R2. The substrate 100 isa semiconductor substrate such as a silicon substrate, a germaniumsubstrate, or a silicon-germanium substrate. The first region is aportion of the chip zone 12 of FIG. 1, and the second region R2 is aportion of the scribe lane zone 14 of FIG. 1.

According to embodiments, a gate line GL is disposed on the substrate100 of the first region R1. For example, the gate line GL has a line orbar shape that extends in a first direction D1 and crosses an activeregion PA defined in the substrate 100 of the first region R1. In thefirst region R1, the substrate 100 includes the active region PA at anupper portion defined by a device isolation pattern 102 p. The deviceisolation pattern 102 p may include, for example, silicon oxide orsilicon oxynitride. Although FIGS. 3 and 4 show one gate line GL,exemplary embodiments of the present inventive concept are not limitedthereto.

According to embodiments, the gate line GL includes a gate dielectricpattern 110 p, a lower gate pattern 115 p, an upper gate pattern 120 p,and a gate capping pattern 125 p that are sequentially stacked. The gatedielectric pattern 110 p includes an insulating material, for example,at least one of silicon oxide, silicon oxynitride, or a high-kdielectric such as a dielectric metal oxide such as hafnium oxide oraluminum oxide that have a dielectric constant greater than that ofsilicon oxide. The lower and upper gate patterns 115 p and 120 p includea conductive material. For example, the lower gate pattern 115 p caninclude doped polysilicon and the upper gate pattern 120 p includes atleast one of a metal such as tungsten, aluminum, titanium, or tantalum,or a conductive metal nitride such as titanium nitride, tantalumnitride, or tungsten nitride. The gate capping pattern 125 p includes aninsulating material, such as silicon oxide, silicon nitride, or siliconoxynitride.

According to embodiments, the gate line GL is provided with gate spacers135 p on its sidewalls that extend in the first direction D1 along thegate line GL. The gate spacers 135 p include at least one of siliconoxide, silicon nitride, or silicon oxynitride. Source/drain regions PSDare disposed in the active region PA on opposite sides of the gate lineGL. The source/drain regions PSD are doped with p- or n-type impurities.

According to embodiments, a lower interlayer dielectric layer 140 isdisposed on the substrate 100 of the first region R1. The lowerinterlayer dielectric layer 140 covers the sidewalls of the gate lineGL. The lower interlayer dielectric layer 140 includes at least one ofsilicon oxide, silicon nitride, or silicon oxynitride. The lowerinterlayer dielectric layer 140 exposes a top surface of the gate lineGL, but exemplary embodiments of the present inventive concept are notlimited thereto.

According to embodiments, a lower contact plug 152 is disposed on atleast one of opposite sides of the gate line GL, and penetrates thelower interlayer dielectric layer 140 to connect to one of thesource/drain regions PSD. A lower interconnect line 154 connected to thelower contact plug 152 is disposed on the lower interlayer dielectriclayer 140. The lower contact plug 152 and the lower interconnect line154 include the same conductive material. For example, the lower contactplug 152 and the lower interconnect line 154 can include at least one ofa metal such as tungsten, titanium, or tantalum, or a conductive metalnitride such as titanium nitride, tantalum nitride, or tungsten nitride.In some embodiments, the lower contact plug 152 and the lowerinterconnect line 154 are simultaneously formed to constitute a singleunitary structure.

According to embodiments, an alignment key AK is disposed on thesubstrate 100 of the second region R2. The alignment key AK includes analignment key pattern KP and an alignment key trench Tk. The alignmentkey trench Tk vertically penetrates at least a portion of the alignmentkey pattern KP. In other words, the alignment key AK is a trench-typealignment key. Although the alignment key AK is illustrated as havingone alignment key trench Tk, exemplary embodiments of the presentinventive concept are not limited thereto. In some embodiments, thealignment key AK includes an alignment key pattern KP and a plurality ofalignment key trenches Tk that penetrate the alignment key pattern KP.

According to embodiments, the alignment key pattern KP includes a firstsub-alignment key pattern KP1 and a second sub-alignment key patternKP2. The first sub-alignment key pattern KP1 includes a bufferdielectric pattern 110 k, a first conductive pattern 115 k, a secondconductive pattern 120 k, and a capping dielectric pattern 125 k. Insome embodiments, the alignment key trench Tk vertically penetrates aportion of the first sub-alignment key pattern KP1. For example, thealignment key trench Tk penetrates the capping dielectric pattern 125 kand the second conductive pattern 120 k to expose the first conductivepattern 115 k through the alignment key trench Tk.

According to a present inventive concept, the alignment key trench Tkincludes portions having different widths from each other. For example,the alignment key trench Tk includes an upper trench T1 having a firstwidth W1 and a lower trench T2 having a second width W2 less than thefirst width W1. The lower trench T2 extends downward from the uppertrench T1. The first and second widths W1 and W2 of the alignment keytrench Tk are measured in a second direction D2. The second direction D2is, for example, perpendicular to the first direction D1. The uppertrench T1 vertically penetrates a portion of the capping dielectricpattern 125 k. In this configuration, the upper trench T1 is formed inthe capping dielectric pattern 125 k. The upper trench T1 has a depth d1less than a thickness of the capping dielectric pattern 125 k. The lowertrench T2 extends from the upper trench T1 to penetrate the cappingdielectric pattern 125 k and the second conductive pattern 120 k, toexpose the first conductive pattern 115 k through the lower trench T2.The alignment key trench Tk has a depth d of greater than or equal toabout 30 nm, which is a sum of the depth d1 of the upper trench T1 and adepth d2 of the lower trench T2. For example, the depth d of thealignment key trench Tk is in the range from about 30 nm to about 500nm. The width W2 of the lower trench T2 is greater than or equal toabout 100 nm. For example, the width W2 of the lower trench T2 is in therange from about 100 nm to about 5,000 nm.

According to embodiments, the second sub-alignment key pattern KP2includes a lower conductive pattern 156 and an upper conductive pattern158. The lower conductive pattern 156 is disposed in the lower trench T2and partially fills the lower trench T2. For example, the lowerconductive pattern 156 includes sidewall conductive patterns 156 sdisposed on sidewalls of the lower trench T2 and an interconnectconductive pattern 156 c that connects bottom ends of the sidewallconductive patterns 156 s. The interconnect conductive pattern 156 c isin contact with the first conductive pattern 115 k exposed through thelower trench T2. The sidewall conductive patterns 156 s and theinterconnect conductive pattern 156 c constitute a single unitarystructure. The upper conductive pattern 158 is disposed on a top surfaceof the capping dielectric pattern 125 k. The upper conductive pattern158 has inner sidewalls aligned with sidewalls of the capping dielectricpattern 125 k that are exposed through the upper trench T1.

According to embodiments, the buffer dielectric pattern 110 k, the firstconductive pattern 115 k, the second conductive pattern 120 k, and thecapping dielectric pattern 125 k of the first sub-alignment key patternKP1 have the same materials, respectively, as the gate dielectricpattern 110 p, the lower gate pattern 115 p, the upper gate pattern 120p, and the gate capping pattern 125 p of the gate line GL. The bufferdielectric pattern 110 k includes at least one of, for example, siliconoxide, silicon oxynitride, or a high-k dielectric such as a dielectricmetal oxide such as hafnium oxide or aluminum oxide that have adielectric constant greater than that of silicon oxide. For example, thefirst conductive pattern 115 k includes doped polysilicon, and thesecond conductive pattern 120 k includes at least one of a metal such astungsten, aluminum, titanium, or tantalum, or a conductive metal nitridesuch as titanium nitride, tantalum nitride, or tungsten nitride. Thecapping dielectric pattern 125 k may include, for example, siliconoxide, silicon nitride, or silicon oxynitride.

According to embodiments, the lower conductive pattern 156 and the upperconductive pattern 158 of the second sub-alignment key pattern KP2include the same material as the lower contact plug 152 and the lowerinterconnect line 154. For example, the lower contact pattern 156 andthe upper interconnect line 158 include at least one of a metal such astungsten, titanium, or tantalum, or a conductive metal nitride such astitanium nitride, tantalum nitride, or tungsten nitride.

According to embodiments, during a method of fabricating a semiconductordevice, the alignment key trench Tk is provided with mask layers withdifferent etch selectivities which are removed after a patterningprocess that uses the mask layers. After removing the mask layers fromthe alignment key trench Tk, the mask layers may partially remain to actas lifting failure sources. In some embodiments, the alignment key AKare configured to suppress lifting failure. This will be described indetail in the following description of a method of fabricating asemiconductor device.

According to embodiments, an upper interlayer dielectric layer isdisposed on an entire surface of the substrate 100. On the first regionR1, the upper interlayer dielectric layer covers the lower interconnectline 154. On the second region R2, the upper interlayer dielectric layerfills the alignment key trench Tk. The upper interlayer dielectric layerincludes silicon oxide, silicon nitride, or silicon oxynitride.

FIGS. 5A to 5C are cross-sectional views, corresponding to line II-II′of FIG. 3, that illustrate other examples of the alignment key shown inFIGS. 3 and 4. For brevity of the description, different configurationswill be described.

Referring to FIG. 5A, according to embodiments, the lower conductivepattern 156 of the second sub-alignment key pattern KP2 includes onlythe sidewall conductive patterns 156 s. That is, the interconnectconductive pattern 156 c of FIGS. 3 and 4 is omitted. The sidewallconductive patterns 156 s are separately disposed on the sidewalls ofthe lower trench T2. The first conductive pattern 115 k have a topsurface that defines a floor surface of the lower trench T2 which isexposed through the lower conductive pattern 156.

Referring to FIG. 5B, according to embodiments, the second sub-alignmentkey pattern KP2 includes only the lower conductive patterns 156. Thatis, the upper conductive pattern 158 of FIGS. 3 and 4 is omitted.

Referring to FIG. 5C, according to embodiments, the second sub-alignmentkey pattern KP2 includes only the sidewall conductive patterns 156 s.That is, the interconnect conductive pattern 156 c and the upperconductive pattern 158 of FIGS. 3 and 4 are omitted.

FIGS. 6 to 14 are cross-sectional views, corresponding to lines I-I′ andII-II′ of FIG. 3, that illustrate a method of fabricating asemiconductor device according to exemplary embodiments of the presentinventive concept. FIGS. 15 and 16 are cross-sectional views,corresponding to lines I-I′ and II-II′ of FIG. 3, that illustratecomparative examples that are compared with exemplary embodiments of thepresent inventive concept. For brevity of the description, a repetitiveexplanation will be omitted.

Referring to FIGS. 3 and 6, according to embodiments, a substrate 100 isprovided that includes a first region R1 and a second region R2. Anactive region PA is defined by forming a device isolation pattern 102 pin the first region R1 of the substrate 100. For example, a shallowtrench isolation (STI) process can be performed to form the deviceisolation pattern 102 p.

According to embodiments, a first dielectric layer 110, a lowerconductive layer 115, an upper conductive layer 120, and a seconddielectric layer 125 are sequentially formed on the substrate 100. Thefirst dielectric layer 110, the lower conductive layer 115, the upperconductive layer 120, and the second dielectric layer 125 cover all ofthe first and second regions R1 and R2. The first dielectric layer 110includes at least one of, for example, silicon oxide, siliconoxynitride, or a high-k dielectric such as a dielectric metal oxide suchas hafnium oxide or aluminum oxide that have a dielectric constantgreater than that of silicon oxide. For example, the lower conductivelayer 115 includes doped polysilicon, and the upper conductive layer 120includes at least one of a metal such as tungsten, aluminum, titanium,or tantalum, or a conductive metal nitride such as titanium nitride,tantalum nitride, or tungsten nitride. The second dielectric layer 125includes, for example, silicon oxide, silicon nitride, or siliconoxynitride. The first dielectric layer 110, the lower conductive layer115, the upper conductive layer 120, and the second dielectric layer 125can be formed through a deposition process such as CVD or PVD.

Referring to FIGS. 3 and 7, according to embodiments, a first maskpattern M1 is formed on the substrate 100. The second dielectric layer125 of the first region R1 includes a portion, where a gate line GL isformed, that is covered by the first mask pattern M1 and a remainingportion that is exposed through the first mask pattern M1. The seconddielectric layer 125 of the second region R2 is completely covered bythe first mask pattern M1. The first mask pattern M1 includes a hardmaskpattern or a photoresist pattern.

Referring to FIGS. 3 and 8, according to embodiments, the substrate 100undergoes an etching process using the first mask pattern M1 as anetching mask. A gate line GL is then formed on the substrate 100 of thefirst region R1. The gate line GL includes a gate dielectric pattern 110p, a lower gate pattern 115 p, an upper gate pattern 120 p, and a gatecapping pattern 125 p that are respectively formed by patterning thefirst dielectric layer 110, the lower conductive layer 115, the upperconductive layer 120, and the second dielectric layer 125 of the firstregion R1. During the formation of the gate line GL, the first maskpattern M1 protects the layers 110, 115, 120, and 125 of the secondregion R2. After the formation of the gate line GL, the first maskpattern M1 is removed.

According to embodiments, gate spacers 135 p are formed on sidewalls ofthe gate line GL. For example, the gate spacers 135 p can be formed byforming a gate spacer layer on an entire surface of the substrate 100and then performing a blanket anisotropic etching process. The gatespacer layer includes at least one of silicon oxide, silicon nitride, orsilicon oxynitride.

According to embodiments, source/drain regions PSD are formed in thesubstrate 100 on opposite sides of the gate line GL. For example, thesource/drain regions PSD can be formed by an ion implantation processusing the gate line GL as an ion implantation mask.

Referring to FIGS. 3 and 9, according to embodiments, a lower interlayerdielectric layer 140 is formed on the substrate 100 of the first regionR1. For example, the lower interlayer dielectric layer 140 can be formedby covering the entire surface of the substrate 100 with an insulatinglayer and then performing a planarization process on the insulatinglayer to expose a top surface of the gate line GL. As a result, thelower interlayer dielectric layer 140 has a top surface whose height issubstantially the same as that of the top surface of the gate line GL.During the planarization process, the lower interlayer dielectric layer140 is completely removed from the second region R2.

According to embodiments, a second mask pattern M2 is formed on thesubstrate 100. The second mask pattern M2 has first openings OP1 on thefirst region R1 and a second opening OP2 on the second region R2. Thefirst openings OP1 are shaped as a hole and overlap the source/drainregions PSD on opposite sides of the gate line GL. The second openingOP2 is a trench that extends in the first direction D1. The secondopening OP2 has a width Wa that corresponds to the second width W2 ofthe lower trench T2 shown in FIGS. 3 and 4. The second mask pattern M2includes a hardmask pattern or a photoresist pattern.

Referring to FIGS. 3 and 10, according to embodiments, an etchingprocess is performed using the second mask pattern M2 as an etching maskto etch the lower interlayer dielectric layer 140 on portions exposedthrough the first openings OP1. The etching process uses an etchant onthe substrate 100 that has a low etch rate and is performed until a topsurface of the substrate 100 is exposed. Accordingly, lower contactholes 145 are formed that penetrate the lower interlayer dielectriclayer 140 and expose the source/drain regions PSD. The etching processalso sequentially etches the second dielectric layer 125 and the upperconductive layer 120 to form a preliminary alignment key trench Tp thatexposes the lower conductive layer 115. The lower conductive layer 115is not removed from the second region R2 during the etching process thatforms the lower contact holes 145 since the lower conductive layer 115is formed of doped polysilicon. In other words, when the preliminaryalignment key trench Tp is simultaneously formed with the lower contactholes 145, the lower conductive layer 115 of the second region R2 actsas an etch stop layer. The preliminary alignment key trench Tp has awidth that corresponds to the width Wa of the second opening OP2. Afterforming the lower contact holes 145 and the preliminary alignment keytrench Tp, the second mask pattern M2 is removed.

Referring to FIGS. 3 and 11, according to embodiments, a lowerinterconnect line layer 150 is formed on the substrate 100. The lowerinterconnect line layer 150 of the first region R1 completely fills thelower contact holes 145 and covers the top surface of the lowerinterlayer dielectric layer 140. The lower interconnect line layer 150of the second region R2 partially fills the preliminary alignment keytrench Tp and covers a top surface of the second dielectric layer 125.The lower interconnect line layer 150 includes at least one of a metalsuch as tungsten, titanium, or tantalum, or a conductive metal nitridesuch as titanium nitride, tantalum nitride, or tungsten nitride.

Referring to FIGS. 3 and 12, according to embodiments, an organic masklayer 162 and a hardmask layer 164 are sequentially formed on thesubstrate 100. The organic mask layer 162 is formed of a material havingan etch selectivity with respect to the hardmask layer 164. For example,the organic mask layer 162 can be formed of an SOH (spin on hardmask)layer. The SOH layer may include a carbon-based SOH layer or asilicon-based SOH layer. The hardmask layer 164 includes a silicon oxidelayer, a silicon oxynitride layer, or a silicon nitride layer.

According to embodiments, on the first region R1, the organic mask layer162 and the hardmask layer 164 cover the lower interconnect line layer150 and have a flat top surface. On the second region R2, the organicmask layer 162 covers the lower interconnect line layer 150 andcompletely fills the preliminary alignment key trench Tp. The organicmask layer 162 has a stepped top surface on the second region R2. Forexample, on the second region R2, the organic mask layer 162 has aconcave top surface that protrudes toward the substrate 100 at a portionthat overlaps the preliminary alignment key trench Tp. On the secondregion R2, the hardmask layer 164 has a top surface whose profile issubstantially the same as that of the top surface of the organic masklayer 162.

According to embodiments, a third mask pattern M3 is formed on thehardmask layer 164. The third mask pattern M3 has a third opening OP3 onthe first region R1 and a fourth opening OP4 on the second region R2. Onthe first region R1, the third opening OP3 overlaps the lowerinterconnect line layer 150 except at portions to he formed into a lowerinterconnect line (see 154 of FIG. 14). On the second region R2, thefourth opening OP4 overlaps the stepped surfaces of the organic masklayer 162 and the hardmask layer 164. The fourth opening OP4 extends inthe first direction D1 along the preliminary alignment key trench Tp.The fourth opening OP4 has a width Wb greater than the width Wa of thepreliminary alignment key trench Tp. The third mask pattern M3 includes,for example, a photoresist pattern.

In some embodiments, the organic mask layer 162 includes an organicmaterial formed by a deposition process. For example, the organic masklayer 162 can be formed of an amorphous carbon layer (ACL). In thiscase, as shown in FIG. 13, the organic mask layer 162 partially fillsthe preliminary alignment key trench Tp. Likewise as shown in FIG. 12,on the second region R2, the organic mask layer 162 also has a concavetop surface at a portion that overlaps the preliminary alignment keytrench Tp. The formation of the organic mask layer 162 as shown in FIG.12 will hereinafter be described in detail.

Referring to FIGS. 3 and 14, according to embodiments, the hardmasklayer 164, the organic mask layer 162, and the lower interconnect linelayer 150 are sequentially etched by an etching process that isperformed on the substrate 100 on which the third mask pattern M3 isformed. Consequently, on the first region R1, the lower interconnectline layer 150 on the lower interlayer dielectric layer 140 is patternedto form a lower interconnect line 154. The lower interconnect line layer150 that remains in the lower contact holes 145 forms the lower contactplugs 152. The lower interconnect line layer 150 of the second region R2is also patterned to form an upper conductive pattern 158 and a lowerconductive pattern 156. When the upper and lower conductive patterns 158and 156 are formed, the second dielectric layer 125 of the second regionR2 is partially etched to form an upper trench T1 in the seconddielectric layer 125 of the second region R2. The preliminary alignmentkey trench Tp has a lower portion below the upper trench T1. Theremaining lower portion of the preliminary alignment key trench Tp formsthe lower trench T2. On the second region R2, the layers 110, 115, 120,and 125 remain after the lower and upper conductive patterns 156 and 158are formed. The remaining first dielectric layer 110, lower conductivelayer 115, upper conductive layer 120, and second dielectric layer 125form the buffer dielectric pattern 110 k, a first conductive pattern 115k, a second conductive pattern 120 k, and a capping dielectric pattern125 k. According to exemplary embodiments of the present inventiveconcept, during the patterning of the lower interconnect line layer 150,the third mask pattern M3 and the hardmask layer 164 are completelyremoved, but the organic mask layer 162 may remain. An ashing process isused to remove the remaining organic mask layer 162. Through theaforementioned processes, a semiconductor device of FIGS. 3 and 4 can befabricated.

According to embodiments, to form the lower interconnect line 154, thethird mask pattern M3 is formed to completely cover the hardmask layer164 of the second region R2. In this case, as shown in FIG. 15, ahardmask layer portion 164 r may remain on the preliminary alignment keytrench Tp even after the lower interconnect line 154 is formed. Thepresence of the hardmask layer portion 164 r may be due to non-uniformetching caused by the stepped profile of the hardmask layer 164. Eventhough an ashing process is subsequently performed to remove the organicmask layer 162, as shown in FIG. 16, the hardmask layer portion 164 rmay still remain because of its etch selectivity with respect to theorganic mask layer 162. The remaining hardmask layer portion 164 r canact as a lifting failure source in subsequent processes. However,according to exemplary embodiments of the present inventive concept, asthe third mask pattern M3 has the fourth opening OP4 through which thestepped portion of the hardmask layer 164 is exposed, the hardmask layer164 is completely removed when the lower interconnect line layer 150 ispatterned. Lifting failure due to residue of the hardmask 164 can beprevented from occurring, and thus it is possible to provide asemiconductor device having enhanced process yield and reliability.

According to embodiments, during the steps shown in FIGS. 12 and 14, thelower interconnect line layer 150 can be differently patterned to formthe alignment key patterns KP described with reference to FIGS. 5A to5C.

FIG. 17 is a cross-sectional view, corresponding to lines I-I′ andII-II′ of FIG. 3, that illustrates a semiconductor device according toexemplary embodiments of the present inventive concept. In theembodiment that follows, the first region R1 is configured substantiallythe same as that described with reference to FIGS. 3 and 4. The secondregion R2 is also configured substantially the same as that describedwith reference to FIGS. 3 and 4, except for differences in theconfiguration of the first sub-alignment key pattern KP1 and the depthd2 of the lower trench T2. For brevity of the description, differentconfigurations will be principally described.

Referring to FIGS. 3 and 17, according to embodiments, the lower trenchT2 that extends downward from the upper trench T1 penetrates the cappingdielectric pattern 125 k, the second conductive pattern 120 k, the firstconductive pattern 115 k, and the buffer dielectric pattern 110 k toexpose the substrate 100 through the lower trench T2. In other words,the alignment key trench Tk fully penetrates the first sub-alignment keypattern KP1. The sidewall conductive patterns 156 s and the interconnectconductive pattern 156 c in the lower trench T2 are therefore be incontact with a top surface of the substrate 100 exposed through thelower trench T2. Although FIG. 17 illustrates the upper trench T1 ashaving depth d1 that is less than the depth d2 of the lower trench T2,embodiments are not limited thereto. In other embodiments, the depth d1of the upper trench T1 may be greater than the depth d2 of the lowertrench T2.

According to embodiments, the first sub-alignment key pattern KP1further includes dielectric spacers 135 k interposed between one of thesidewall conductive patterns 156 s and one of sidewalls of the lowertrench T2. That is, the first sub-alignment key pattern KP1 includes thebuffer dielectric pattern 110 k, the first conductive pattern 115 k, thesecond conductive pattern 120 k, the capping dielectric pattern 125 k,and further includes the dielectric spacers 135 k disposed on sidewallsthereof. The dielectric spacers 135 k extend in the first direction D1along the sidewalls of the lower trench T2. The dielectric spacers 135 kinclude the same material as the gate spacers 135 p. For example, thedielectric spacers 135 k includes at least one of silicon oxide, siliconnitride, or silicon oxynitride. Other components are substantially thesame as those described with reference to FIGS. 3 and 4, and detaileddescriptions thereof are omitted.

FIGS. 18A to 18C are cross-sectional views, corresponding to line II-II′of FIG. 3, that illustrate other examples of the alignment keys shown inFIGS. 3 and 17. In the embodiments that follow, configurations differentfrom the alignment key of FIGS. 3 and 17 will be principally describedfor brevity of the description.

Referring to FIG. 18A, according to other embodiments, the lowerconductive pattern 156 of the second sub-alignment key pattern KP2includes only the sidewall conductive patterns 156 s. That is, theinterconnect conductive pattern 156 c of FIGS. 3 and 17 is omitted. Thesidewall conductive patterns 156 s are separately disposed on thesidewalls of the lower trench T2, and the substrate 100 has an exposedtop surface that defines a floor of the lower trench T2.

Referring to FIG. 18B, according to other embodiments, the secondsub-alignment key pattern KP2 includes only the lower conductivepatterns 156. That is, the upper conductive pattern 158 of FIGS. 3 and17 is omitted. Referring to FIG. 18C, according to other embodiments,the second sub-alignment key pattern KP2 includes only the sidewallconductive patterns 156 s. That is, the interconnect conductive pattern156 c and the upper conductive pattern 158 of FIGS. 3 and 17 areomitted.

FIGS. 19 to 22 are cross-sectional views, corresponding to lines I-I′and II-II′ of FIG. 3, that illustrate a method of fabricating asemiconductor device according to exemplary embodiments of the presentinventive concept. For brevity of the description, a repetitiveexplanation will be omitted.

Referring to FIGS. 3 and 19, according to embodiments, a first maskpattern M1 a is formed on a resultant structure of FIG. 6. On the firstregion R1, the second dielectric layer 125 is partially covered with thefirst mask pattern M1 a at a portion where the gate line GL is to beformed. On the second region R2, the first mask pattern M1 a includes afifth opening OP5 through which the second dielectric layer 125 isexposed. The fifth opening OP5 is a trench that extends in the firstdirection D1. The fifth opening OP5 has a width Wa that corresponds tothe second width W2 of the lower trench T2 shown in FIG. 17.

Referring to FIGS. 3 and 20, according to embodiments, the seconddielectric layer 125, the upper conductive layer 120, the lowerconductive layer 115, and the second dielectric layer 125 aresequentially etched by an etching process using the first mask patternM1 a as an etching mask. The gate line GL is then formed on thesubstrate 100 of the first region R1. On the second region R2, thepreliminary alignment key trench Tp is also formed on the substrate 100that penetrates the second dielectric layer 125, the upper conductivelayer 120, the lower conductive layer 115, and the second dielectriclayer 125, to expose a top surface of the substrate 100. According to anembodiment, when the preliminary alignment key trench Tp is formedsimultaneously with the gate line GL, the preliminary alignment keytrench Tp can be formed deeper than the preliminary alignment key trenchTp of FIG. 10. After forming the gate line GL and the preliminaryalignment key trench Tp, the first mask pattern M1 a is removed.

Referring to FIGS. 3 and 21, according to embodiments, the gate spacers135 p are formed on sidewalls of the gate line GL, and the dielectricspacers 135 k are formed on sidewalls of the preliminary alignment keytrench Tp. For example, the gate spacers 135 p and the dielectricspacers 135 k can be formed by forming a gate spacer layer on an entiresurface of the substrate 100 and then performing a blanket anisotropicetching process. The gate spacer layer may include at least one ofsilicon oxide, silicon nitride, or silicon oxynitride.

According to embodiments, the source/drain regions PSD are formed in thesubstrate 100 on opposite sides of the gate line GL. For example, thesource/drain regions PSD can be formed by an ion implantation processusing the gate line GL as an ion implantation mask.

Referring to FIGS. 3 and 22, according to embodiments, the lowerinterlayer dielectric layer 140 is formed on the substrate 100 of thefirst region R1. The lower interlayer dielectric layer 140 includes thelower contact holes 145 that expose the source/drain regions PSD. Thelower interlayer dielectric layer 140 and the lower contact holes 145are formed by the same processes as those discussed with reference toFIGS. 9 and 10. The preliminary alignment key trench Tp is filled withthe lower interlayer dielectric layer 140, which is removed from thesecond region R2 during or after the formation of the lower contactholes 145.

Thereafter, according to embodiments, processes identical or similar tothose described with reference to FIGS. 11 to 14 may be executed tofabricate the semiconductor device of FIGS. 3 and 17.

FIG. 23 is a cross-sectional view, corresponding to lines I-I′ andII-II′ of FIG. 3, that illustrates a semiconductor device according toexemplary embodiments of the present inventive concept. In theembodiment that follows, the first region R1 is configured substantiallythe same as that described with reference to FIGS. 3 and 4. The secondregion R2 is configured substantially the same as that described withreference to FIGS. 3 and 17, except that the alignment key AK is formedin a field region. For brevity of the description, differentconfigurations will be principally explained.

Referring to FIGS. 3 and 23, according to embodiments, the alignment keyAK is disposed in a field region, i.e., a buried dielectric pattern 102k. The buried dielectric pattern 102 k is formed simultaneously with orafter the formation of the device isolation pattern 102 p of the firstregion R1. For example, the buried dielectric pattern 102 k can beformed by recessing an upper portion of the substrate 100 of the secondregion R2 and depositing an insulating layer in the recessed substrate100 of the second region R2. The buried dielectric pattern 102 k and thedevice isolation pattern 102 p include the same material, such assilicon oxide or silicon oxynitride.

According to embodiments, as the alignment key AK is formed on theburied dielectric pattern 102 k, the buried dielectric pattern 102 k canexperience over-etching at its upper portion. As a result, the lowertrench T2 may have a floor surface that is recessed into the burieddielectric pattern 102 k, and the lower conductive pattern 156 is alsoformed inside the recessed portion of the buried dielectric pattern 102k. In this configuration, a top surface of the substrate 100 ispositioned higher than the floor surface of the lower trench 12 and abottom surface of the lower conductive pattern 156. Other components aresubstantially the same as those described with reference to FIGS. 3 and17, and detailed descriptions thereof are omitted.

FIGS. 24A to 24C are cross-sectional views, corresponding to line II-II′of FIG. 3, that illustrate other examples of the alignment key shown inFIGS. 3 and 23. Referring to FIGS. 24A to 24C, the examples of FIGS. 18Ato 18C can be incorporated into the embodiment of FIG. 23. For example,as shown in FIG. 24A, the lower conductive pattern 156 of the secondsub-alignment key pattern KP2 may include only the sidewall conductivepatterns 156 s. The sidewall conductive patterns 156 s may be separatelydisposed on the sidewalls of the lower trench T2, and the burieddielectric pattern 102 k may thus have an exposed top surface thatdefines the floor of the lower trench T2. Alternatively, as shown inFIG. 24B, the second sub-alignment key pattern KP2 may include only thelower conductive patterns 156. FIG. 24C illustrates another alternativeembodiment, in which the second sub-alignment key pattern KP2 includesonly the sidewall conductive patterns 156 s.

FIG. 25 is a plan view that illustrates a semiconductor device accordingto exemplary embodiments of the present inventive concept. FIG. 26 is across-sectional view taken along lines A-A′, B-B′, and C-C′ of FIG. 25.For the sake of brevity, a repetitive description will be omitted.

Referring to FIGS. 25 and 26, according to embodiments, a substrate 100includes a first region R1 and a second region R2. The first region R1is a portion of the chip zone 12 of FIG. 1, and the second region R2 isa portion of the scribe lane zone 14 of FIG. 1. The first region R1includes a cell region CR on which memory cells are formed and aperipheral circuit region PR on which peripheral circuits that controlthe memory cells are formed. The gate line GL, the source/drain regionsPSD, the lower contact plugs 152, and the lower interconnect lines 154are provided on the peripheral circuit region PR, and the alignment keyAK is provided on the second region R2. In an embodiment that follows,the peripheral circuit region PR and the second region R2 are configuredsubstantially the same as those of FIGS. 3 and 4, and detaileddescriptions thereof are omitted. In addition, the embodiments of thealignment key AK shown in FIGS. 5A to 5C, 17, 18A to 18C, 23, and 24A to24C can be incorporated into this embodiment.

According to embodiments, the substrate 100 of the cell region CRincludes device isolation pattern 102 c, which defines cell activeregions CA. The cell active regions CA have a bar shape whoselongitudinal axis extends in a third direction that crosses the firstand second directions D1 and D2, and are arranged parallel to eachother.

According to embodiments, word lines WL are provided buried in thesubstrate 100 of the cell region CR. For example, each of the cellactive regions CA crosses a pair of the word lines WL. The word lines WLextend in the first direction D1, and are spaced apart from each otheralong the second direction 1D2 perpendicular to the first direction D1.A cell gate dielectric pattern 106 is disposed between the substrate 100and the word lines WL. The cell gate dielectric pattern 106 includes adielectric material, such as at least one of a silicon oxide layer, asilicon oxynitride layer, or a high-k dielectric layer. The word linesWL include a conductive material, such as at least one of dopedpolysilicon, a metal, or a conductive metal nitride. Word line cappingpatterns 108 are disposed on the word lines WL. The word line cappingpattern 108, the word line WL, and the cell gate dielectric pattern 106are buried in grooves 104 formed in the substrate 100 of the cell regionCR. The word line capping patterns 108 can include, for example, siliconoxide, silicon nitride, or silicon oxynitride.

According to embodiments, each of the cell active regions CA includes afirst source/drain region SD1 at a portion between a pair of the grooves104 and a pair of second source/drain regions SD2 at opposite edges.

According to embodiments, cell conductive lines CL are disposed on thesubstrate 100 of the cell region CR. The cell conductive lines CL extendside by side in the second direction D2 and cross the word lines WL.Each of the cell conductive lines CL is connected to each of a pluralityof first source/drain regions SD1 arranged in the second direction D2.For example, the cell conductive lines CL can be bit lines. Each of thecell conductive lines CL includes a first cell conductive line 115 c, asecond cell conductive line 120 c, and a cell capping line 125 c thatare sequentially stacked. The first cell conductive line 115 c includesthe same material as the lower gate pattern 115 p or the firstconductive pattern 115 k. For example, the first cell conductive line115 c can include a doped semiconductor material, such as dopedpolysilicon. The second cell conductive line 120 c includes the samematerial as the upper gate pattern 120 p or the second conductivepattern 120 k. For example, the second cell conductive line 120 c caninclude at least one of a metal, such as tungsten, titanium, ortantalum, or a conductive metal nitride, such as titanium nitride,tantalum nitride, and/or tungsten nitride. The cell capping line 125 cincludes the same material as the gate capping pattern 125 p or thecapping dielectric pattern 125 k. For example, the cell capping line 125c may include silicon oxide, silicon nitride, or silicon oxynitride.

According to embodiments, each of the cell conductive lines CL furtherincludes interconnect contacts 215 at portions that overlap the firstsource/drain regions SD1, and which penetrate the first cell conductiveline 115 c. The interconnect contacts 215 include a doped semiconductormaterial, such as doped silicon. A cell buffer dielectric pattern 110 cis interposed between the substrate 100 and the first cell conductiveline 115 c. The interconnect contacts 215 penetrate the cell bufferdielectric pattern 110 c into an upper portion of the substrate 100. Thecell buffer dielectric pattern 110 c includes silicon oxide.

According to embodiments, cell dielectric liners 135 c are disposed onsidewalls of the cell conductive lines CL. The cell dielectric liners135 c extend in the second direction D2 along the cell conductive linesCL. The cell dielectric liners 135 c include at least one of, forexample, silicon oxide, silicon nitride, or silicon oxynitride.

According to embodiments, the substrate 100 of the cell region CR alsoincludes cell contact plugs 149 disposed thereon that are connected tothe second source/drain regions SD2. Each of the cell contact plugs 149includes a cell lower contact LC in contact with the second source/drainregion SD2 and a cell upper contact LP on the cell lower contact LC. Thecell lower contact LC includes, for example, doped polysilicon. The cellupper contact LP includes the same material as the lower contact plug152, the lower interconnect line 154, the lower conductive pattern 156,or the upper conductive pattern 158. For example, the cell upper contactLP can include at least one of a metal, such as tungsten, titanium, ortantalum, or a conductive metal nitride such as titanium nitride,tantalum nitride, or tungsten nitride. Dielectric fences 147 aredisposed between the cell contact plugs 149 and the cell conductivelines CL. The dielectric fences 147 include, for example, a siliconnitride layer or a silicon oxynitride layer. A portion of the cell uppercontact LP extends onto a top surface of the dielectric fence 147.

According to embodiments, an upper interlayer dielectric layer 170 isdisposed on the substrate 100. On the first region R1, the upperinterlayer dielectric layer 170 covers the cell upper contacts LP andthe lower interconnect lines 154. On the second region R2, the upperinterlayer dielectric layer 170 fills the alignment key trench Tk whilecovering the upper conductive pattern 158. The upper interlayerdielectric layer 170 includes, for example, silicon oxide, siliconnitride, or silicon oxynitride.

According to embodiments, data storage elements DSP are disposed on theupper interlayer dielectric layer 170 of the cell region CR. Each of thedata storage elements DSP is a capacitor. For example, the data storageelements DSP can include bottom electrodes each of which is connected toone of the cell upper contacts LP, a top electrode that covers thebottom electrodes, and a dielectric layer interposed between the bottomelectrodes and the top electrode. The top electrode is a commonelectrode that covers the bottom electrodes. In some embodiments, eachof the bottom electrodes has a hollow cylindrical shape. The bottomelectrodes and the top electrode include a impurity-doped silicon, ametal, or a metal compound. The dielectric layer may be a single layer,or a combination thereof, and includes at least one of a metal oxidesuch as HfO₂, ZrO₂, Al₂O₃, La₂O₃, Ta₂O₃, and TiO₂, and a perovskitedielectric material such as SrTiO₃(STO), (Ba,Sr)TiO₃(BST), BaTiO₃, PZT,and PLZT. Although FIGS. 25 and 26 show that the data storage elementsDSP are connected to the cell upper contact LP through interconnectplugs 172 in the upper interlayer dielectric layer 170, embodiments arenot limited thereto.

In some embodiments, each of the data storage elements DSP includes avariable resistance structure. The variable resistance structure can bechanged by a programming operation into one of a plurality of statesthat have different resistance values. In some embodiments, the variableresistance structure is a magnetic tunnel junction pattern that uses itsmagnetization directions. The magnetic tunnel junction pattern includesa reference magnetic pattern having a unidirectionally fixedmagnetization direction, a free magnetic pattern having a magnetizationdirection that can be changed to be parallel or antiparallel to themagnetization direction of the reference magnetic pattern, and a tunnelbarrier between the reference and free magnetic patterns. In otherembodiments, the variable resistance structure includes a phase changematerial. The phase change material can change into an amorphous stateor a crystalline state based on the temperature or the time heat isapplied by a programming operation. The phase change material has agreater resistivity in the amorphous state than in the crystallinestate. For example, the phase change material can include at least onechalcogenide element, such as Te or Se. In some embodiments, thevariable resistance structure includes a transition metal oxide. Anelectrical path can appear or disappear in the transition metal oxidedue to a programming operation. The transition metal oxide has a lowresistance value when an electrical path is generated and a highresistance value when the electrical path is destroyed.

According to exemplary embodiments of the present inventive concept, thealignment key can be configured to include a trench and completelyremove the mask layers from the trench. It is thus possible to suppresslifting failure of the mask layers that are not removed from but remainin the trench. Consequently, a semiconductor device can have enhancedprocess yield and reliability.

Although embodiments of the present disclosure have been described inconnection with the exemplary embodiments as illustrated in theaccompanying drawings, it will be understood to those skilled in the artthat various changes and modifications may be made without departingfrom the technical spirit and features of exemplary embodiments of thepresent disclosure. It thus should be understood that theabove-described exemplary embodiments are not limiting but illustrativein all aspects.

What is claimed is:
 1. A semiconductor device, comprising: an alignmentkey on a substrate, wherein the alignment key comprises: a firstsub-alignment key pattern that includes a first conductive pattern, asecond conductive pattern, and a capping dielectric pattern that aresequentially stacked on the substrate; an alignment key trench thatpenetrates at least a portion of the first sub-alignment key pattern;and a lower conductive pattern in the alignment key trench, wherein thealignment key trench comprises: an upper trench that is provided in thecapping dielectric pattern that has a first width; and a lower trenchthat extends downward from the upper trench that has a second width lessthan the first width, wherein the lower conductive pattern includessidewall conductive patterns that are separately disposed on oppositesidewalls of the lower trench.
 2. The semiconductor device of claim 1,wherein the lower trench penetrates the second conductive pattern andexposes the first conductive pattern.
 3. The semiconductor device ofclaim 2, wherein the lower conductive pattern further comprises aninterconnect conductive pattern that connects bottom ends of thesidewall conductive patterns. wherein the interconnect conductivepattern is in contact with the first conductive pattern exposed throughthe lower trench.
 4. The semiconductor device of claim 1, wherein thelower trench penetrates the second conductive pattern and the firstconductive pattern and exposes the substrate.
 5. The semiconductordevice of claim 4, wherein the lower conductive pattern furthercomprises an interconnect conductive pattern that connects bottom endsof the sidewall conductive patterns, wherein the interconnect conductivepattern is in contact with the substrate exposed through the lowertrench.
 6. The semiconductor device of claim 1, wherein the alignmentkey further comprises an upper conductive pattern on the cappingdielectric pattern, wherein the upper conductive pattern has innersidewalls aligned with sidewalls of the capping dielectric pattern,wherein the sidewalls of the capping dielectric pattern are exposedthrough the upper trench.
 7. The semiconductor device of claim 1,wherein the upper trench has a depth that is less than a thickness ofthe capping dielectric pattern.
 8. The semiconductor device of claim 1,wherein the first sub-alignment key pattern comprises dielectricspacers, each of which is interposed between one of the oppositesidewalls of the lower trench and one of the sidewall conductivepatterns.
 9. The semiconductor device of claim 1, further comprising aburied dielectric pattern in the substrate below the first sub-alignmentkey pattern, wherein the lower trench penetrates the second and firstconductive patterns and extends into the buried dielectric pattern. 10.The semiconductor device of claim 1, wherein the substrate comprises afirst region and a second region around the first region, the alignmentkey being disposed in the second region, and wherein the semiconductordevice further comprises a gate line that includes a gate dielectricpattern, a lower gate pattern, an upper gate pattern, and a gate cappingpattern that are sequentially stacked on the first region.
 11. Thesemiconductor device of claim 10, wherein the first conductive pattern,the second conductive pattern, and the capping dielectric patterncomprises the same materials, respectively, as the lower gate pattern,the upper gate pattern, and the gate capping pattern.
 12. Thesemiconductor device of claim 10, further comprising: a source/drainregion that is provided in the substrate on either side of the gate linein the first region; and a lower contact plug that is connected to thesource/drain region, wherein the lower conductive pattern includes thesame material as the lower contact plug.
 13. The semiconductor device ofclaim 10, wherein the first sub-alignment key pattern comprises a bufferdielectric pattern between the first conductive pattern and thesubstrate of the second region, wherein the buffer dielectric patternincludes the same material as the gate dielectric pattern.
 14. Thesemiconductor device of claim 10, wherein the first region comprises acell region and a peripheral circuit region, the gate line beingdisposed in the peripheral circuit region, and wherein the semiconductordevice further comprises a cell conductive line that includes a firstcell conductive line, a second cell conductive line, and a cell cappingline that are sequentially stacked in the cell region, the firstconductive pattern, the second conductive pattern, and the cappingdielectric pattern comprising the same materials, respectively, as thefirst cell conductive line, the second cell conductive line, and thecell capping line.
 15. A semiconductor device, comprising: a substratethat includes a chip zone and a scribe lane zone; a gate line in thechip zone; and an alignment key in the scribe lane zone, wherein thegate line comprises a gate dielectric pattern, a lower gate pattern, anupper gate pattern, and a gate capping pattern that are sequentiallystacked on the substrate, wherein the alignment key comprises: a firstsub-alignment key pattern that includes a buffer dielectric pattern, afirst conductive pattern, a second conductive pattern, and a cappingdielectric pattern that are sequentially stacked on the substrate; analignment key trench that penetrates at least a portion of the firstsub-alignment key pattern, the alignment key trench including an uppertrench that vertically penetrates a portion of the capping dielectricpattern and has a first width and a lower trench that extends downwardfrom the upper trench and has a second width less than the first width;and sidewall conductive patterns that are separately disposed onopposite sidewalls of the lower trench, the buffer dielectric pattern,the first conductive pattern, the second conductive pattern, and thecapping dielectric pattern comprising the same materials, respectively,as the gate dielectric pattern, the lower gate pattern, the upper gatepattern, and the gate capping pattern.
 16. A method of fabricating asemiconductor device, comprising the steps of: providing a substratethat includes a first region and a second region; sequentially forming afirst dielectric layer, a lower conductive layer, an upper conductivelayer, and a second dielectric layer on the substrate; forming a firstmask pattern on the substrate that covers a portion of the seconddielectric layer in the first region and completely covers the seconddielectric layer in the second region; etching the substrate using thefirst mask pattern as an etching mask wherein a gate line is formed inthe first region of the substrate, wherein the gate line includes a gatedielectric pattern, a lower gate pattern, an upper gate pattern, and agate capping pattern that are respectively formed by patterning thefirst dielectric layer, the lower conductive layer, the upper conductivelayer, and the second dielectric layer in the first region; removing thefirst mask pattern; forming source/drain regions in the substrate onopposite sides of the gate line; forming a lower interlayer dielectriclayer on the first region of the substrate; forming a second maskpattern on the substrate that has first openings on the first regionthat overlap the source/drain regions and a trench-shaped second openingon the second region; etching portions of the lower interlayerdielectric layer exposed through the first openings using the secondmask pattern to form lower contact holes that penetrate the lowerinterlayer dielectric layer and expose the source/drain regions, whereinthe second dielectric layer and the upper conductive layer of the secondregion are sequentially etched to form a preliminary alignment keytrench that exposes the lower conductive layer; and removing the secondmask pattern.
 17. The method of claim 16, wherein the first mask patternin the second region includes a fifth opening through which the seconddielectric layer is exposed, wherein etching the substrate the firstmask pattern as an etching mask forms the preliminary alignment keytrench in the second region of the substrate that penetrates the seconddielectric layer, the upper conductive layer, the lower conductivelayer, and the second dielectric layer, to expose a top surface of thesubstrate
 18. The method of claim 16, wherein the first mask patternprotects the first dielectric layer, the lower conductive layer, theupper conductive layer, and the second dielectric layer of the secondregion when etching the substrate with the first mask pattern.
 19. Themethod of claim 16, wherein the method further comprises: forming alower interconnect line layer in the substrate, wherein the lowerinterconnect line layer of the first region completely fills the lowercontact holes and covers the top surface of the lower interlayerdielectric layer, and the lower interconnect line layer of the secondregion partially fills the preliminary alignment key trench and covers atop surface of the second dielectric layer; sequentially forming anorganic mask layer and a hardmask layer on the substrate, wherein theorganic mask layer is formed of a material having an etch selectivitywith respect to the hardmask layer, wherein on the first region, theorganic mask layer and the hardmask layer cover the lower interconnectline layer, and on the second region, the organic mask layer covers thelower interconnect line layer and fills the preliminary alignment keytrench; and forming a third mask pattern on the hardmask layer that hasa third opening on the first region and a fourth opening on the secondregion that extends along the preliminary alignment key trench.
 20. Themethod of claim 19, further comprising sequentially etching the hardmasklayer, the organic mask layer, and the lower interconnect line layerusing the third mask pattern as a pattern mask to form a lowerinterconnect line in the first region from the lower interconnect linelayer, wherein the lower interconnect line layer that remains in thelower contact holes forms lower contact plugs, and the lowerinterconnect line layer of the second region is patterned to form anupper conductive pattern and a lower conductive pattern, wherein thesecond dielectric layer of the second region is partially etched to forman upper trench in the second dielectric layer of the second region,wherein a remaining portion of the preliminary alignment key trenchbelow the upper trench forms a lower trench, and wherein the third maskpattern and the hardmask layer are completely removed; and removing theorganic mask layer.